Generally, a liquid crystal display (LCD) includes a liquid crystal panel assembly including two panels provided with two kinds of field generating electrodes such as pixel electrodes and a common electrode and a liquid crystal layer with dielectric anisotropy interposed therebetween. The variation of the voltage difference between the field generating electrodes, i.e., the variation in the strength of an electric field generated by the electrodes changes the transmittance of the light passing through the LCD, and thus desired images are obtained by controlling the voltage difference between the electrodes.
The LCD includes a plurality of pixels with pixel electrodes and red (R), green (G) and blue (B) color filters. The pixels are driven to perform display operation by way of the signals applied thereto through display signal lines. The signal lines include gate lines (or scanning signal lines) for carrying the scanning signals, and data lines for carrying data signals. Each pixel has a thin film transistor (TFT) connected to one of the gate lines and one of the data lines to control the data signals applied to the pixel electrode.
Meanwhile, there are several types of arrangement of the red (R), green (G) and blue (B) color filters. Examples are a stripe type where the color filters of the same color are arranged in the same pixel columns, a mosaic type where the red, green and blue color filters are arranged in turn along the row and column directions, and a delta type where the pixels are arranged zigzag in the column direction and the red, green and blue color filters are arranged in turn. The delta type correctly represents a circle or a diagonal line.
Since the luminance of a conventional LCD is relatively poor, a four color LCD including white pixels are suggested. The addition of the white pixels decreases color concentration and yields the decrease of other pixels, in particular, blue pixels when maintaining the resolution. For the striped arrangement, the addition of the white pixels also requires additional data lines. For the mosaic arrangement, the addition of the white pixels reduces the number of the data lines but increases the number of the gate lines twice.
A technique called sub-pixel rendering may improve the reduction of color concentration, the increase of the data lines in the striped arrangement, and the increase of the gate lines in the mosaic arrangement. However, since the resolution in the row direction is decreased compared with actual resolution, the rendering is not inadequate for a monitor displaying fine images such as texts although it is proper to motion images displayed by TV, etc.